Often instruments and sensors are placed in locations where radio communications are impossible or impractical. Cave walls, walls of narrow gorges and other geological features may block radio transmissions which might otherwise be used to monitor or communicate with such instruments. Known techniques for monitoring such instruments require installation of cables. Often, the physical location of the instruments means that cables to such instruments must be long. Such installations are awkward and time consuming. Such long cables are vulnerable to damage.
In some fields, especially in energy prospecting, seismic charges and waves have been used to communicate information. These techniques often rely on time intervals between nearly identical seismic shots, in essence, these techniques are analogous to Morse Code, where the timing of separate signals conveys information. Other such techniques rely not on true seismic transmission of signals, but instead on the transmission through fluids, like slurry or water.
What is needed, therefore, are techniques for wirelessly communicating data through geological barriers.